Mechanical hedge pruning and topping of commercial pecan trees in the Southwest increases income potential for producers, according to University of Arizona (UA) Extension soil specialist James Walworth.

This common practice helps manage pecan tree size and improve orchard light penetration which can increase nut yields on the lower branches. Pecans are an alternate bearing crop with higher on-year yields and lower off-year yields.

“Hedging in the on-year reduces the amount of nut-bearing wood, fruit load, and is thought to increase nut quality,” Walworth said. “Hedging increases off-year yields and reduces alternate bearing,” Walworth said.

Walworth, along with Richard Heerema, New Mexico State University pecan specialist, discussed pecan tree hedging and topping with the nearly 600 pecan industry members at the 2012 Western Pecan Growers Association Conference in Las Cruces, N.M. held this spring.

Few studies have evaluated the impact of hedging on pecan crop production and quality, Walworth said. Each producer generally adapts a preferred hedging method since no textbook method really exists.

Walworth reported on a UA study conducted on a four-year hedging cycle implemented at the Farmer’s Investment Company’s (FICO) pecan operation located in south central Arizona on mature trees. The cycle included pruning every fourth row during every fourth year.

This program was adopted partly for practicality. Since the orchard covers almost 5,000 acres, it is impractical to prune more than one quarter of the orchard in any given year.

The farm’s Western Schley variety trees were planted in 1969 and are now on 60 x 60-foot spacing. The Wichita variety trees, planted in 1967, are spaced 30-feet apart in rows 60-feet apart. Both blocks are flood irrigated.

Walworth has monitored the pruned Wichita and Western Schley varieties to evaluate the impact of hedging since 2009.

In 2009 and 2010, nuts were collected from individual rows in the Western Schley and Wichita blocks with a self-propelled harvester for the study. A grocery bag-sized sample was collected from each harvested row and then cleaned.

The nuts were graded to separate marketable nuts, sticktights, and pre-germinated nuts. All three categories were weighed. A sub sample of good nuts was counted and weighed to measure the nut size, and then shelled to determine the percent marketable kernel.

Fertilization practices were not adjusted during the hedging cycle.

Here are the study results thus far.